Clinical evidence is revealing that patients suffering from cardiac diseases which affect the contractility of the heart muscle tissue rather than the conduction pathways, generally known as congestive heart failure or CHF, can also benefit from cardiac pacing. CHF is a condition in which a weakened heart cannot pump enough blood to body organs. Heart failure may affect either the right side, left side, or both sides of the heart. As pumping action is lost, blood may back up into other areas of the body, including the liver, gastrointestinal tract, and extremities (right-sided heart failure), or the lungs (left-sided heart failure). Structural or functional causes of heart failure include high blood pressure (hypertension), valvular heart disease, congenital heart diseases, cardiomyopathy, heart tumor, and other heart diseases. Precipitating factors include infections with high fever or complicated infections, use of negative inotropic drugs (such as beta-blockers and calcium channel blocker), anemia, irregular heartbeats (arrhythmias), hyperthyroidism, and kidney disease.
Treatment typically involves pacing on both sides of the heart. In such patients, pacing in the atria and ventricles effectively resynchronizes heart chamber contractions thereby improving hemodynamic function of the heart. Biventricular pacing has proven to be an effective therapy or treating patient with congestive heart failure.
A system and method for monitoring progression of cardiac disease state using physiologic sensors is disclosed in U.S. Pat. No. 6,572,557, by Tchou, et al., issued Jun. 3, 2003, which describes a technique for monitoring physiological parameters associated with the progression, stabilization, or regression of symptoms of heart disease such as congestive heart failure (CHF), which is herein incorporated by reference in its entirety. A system and method for evaluating risk of mortality due to congestive heart failure using physiologic sensors is disclosed in U.S. Pat. No. 6,645,153 by Kroll et al., issued Nov. 11, 2003, which is herein incorporated by reference in its entirety. One method and apparatus for biventricular stimulation and capture monitoring is disclosed in published U.S. Patent application publication number 20010049543, filed May 1, 2001, by Mark Kroll, herein incorporated by reference in its entirety.
Unfortunately, when fitting a patient with an implantable pacing device, it can be difficult to pass a left-side lead into the coronary sinus vein, or the smaller final destination veins, or keep it in stable position. Accordingly, there is a need for alternative techniques of placing a pacing stimulus on the left side of the heart.